Effect of microstructure parameters on tensile toughness of tool steel after deep cryogenic treatment

What is it about?

In this research, effects of microstructural parameters were studied on tensile toughness of a medium carbon-low alloy tool steel. The results showed that the maximum population density of sub-micron sized secondary carbide was obtained after 36 h of soaking time. Also, amount of secondary carbides increased with soaking or tempering times from 2.18 vol% to 12.87 vol%. In addition, high population density and high content of secondary carbides were responsible for tensile toughness enhancement. Therefore, the best results (12-35% improvement in tensile toughness) were obtained for a specimen, which underwent a full treatment cycle consisting of heating, water quenching, soaking at -196ºC for 36 or 48 h and tempering at 200ºC for 1 or 2 h, respectively.

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Why is it important?

Microstructure of an alloy has a significant effect on mechanical properties. Deep cryogenic treatment extends life of tool steels because of microstructure changes.